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bcal, ups, cdc
Dear all,
we had yesterday a meeting with Tim looking in more detail to changing the
length of the bcal.
From space considerations it is possible to enlarge the length of the bcal
by 40 cm, this would give basically overlap between the UPV bcal.
But I think this idea is not to great, because first of all we must also
make the cdc longer to have tracking coverage to separate photons from
charged particles.
In addition the upstream end of the cdc has a lot of material
connectors, electronics and so on with the distance of the UPV from this
material we will get similar problems like with the FCAL if photons
convert early in the FDC material.
The cdc upstream material and the distance from the UPV will make clusters
from photons which convert early make really big.
Paul did you actually simulate what this material does to the lower photon
threshold for the UPV?
I think the best because of the arguments above and of course money issues
is to redesign the UPV and move it much closer to the upstream end of the
cdc.
Discussing this a bit yesterday, it did not seem to be to hard, even so
the opening of the magnet is round.
If you do steps like shown below you can get a petty high fill factor for
square scintillator bars in a circle.
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elke
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